LAUSR

Aims: The purpose of this study is to determine if the combined associations of HbA1c and blood lipid levels with audiometric thresholds are nonadditive, additive, or synergistic. Methods: A retrospective cross-sectional study was performed using the 2009-2010, 2011-2012, and 2015-2016 National Health and Nutritional Examination Survey. Participants were placed into tertial groups based on HbA1c, triglyceride, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels. Two-way analyses of variance were used to measure the combined effect of HbA1c and each lipid on mid- and high-frequency audiometric thresholds. Groups were matched by age and gender among HbA1c and blood lipid groups in three separate datasets. Results: The difference in mid-frequency audiometric thresholds between the lowest and highest level of HbA1c groups was 2.0 dB (P = 0.019) in one data set and 2.6 dB (P = 0.005) in another dataset. The difference in mid-frequency audiometric thresholds was 2.1 dB (P = 0.012) when comparing the lowest and highest triglyceride groups, and 2.4 dB (P = 0.001) when comparing the lowest and highest LDL-C groups. HDL-C levels, high frequency audiometry, and the interaction components were not significant for any analysis. Conclusions: These results indicate that higher HbA1c and blood lipid levels may have an additive effect on mid-frequency audiometric thresholds.